A dental furnace of this type and a method of this type have long been known. Precisely for sintering adapted dental materials it is important to cause the heating up, the actual firing, and indeed the cooling down as well, to proceed according to a predetermined and reproducible scheme in order on the one hand to ensure the required material compaction, but on the other hand also to ensure that the shrinkage takes place uniformly to the entire extent.
For this purpose, the temperature in the interior of the dental furnace is typically controlled with a precisely determined temperature profile. For this purpose, the heating elements are connected to a corresponding control device, and a temperature sensor is normally used.
The temperature sensor is typically arranged in the upper region of the firing chamber serving as working space, the restorations being placed there.
Temperature sensors can therefore be arranged in or on the wall of the firing space, and it is known to use special calibration devices to ensure that the temperature in the interior of the dental furnace follows a predetermined temperature profile.
On the other hand, the heat capacity of the introduced mass is a parameter that influences the heating-up profile of the dental material. The heating-up rate is typically lower if large masses are used, and higher if small masses are used. In order to compensate for this effect, it is possible to detect the introduced mass beforehand and to provide calibration curves for different masses. However, this is complicated and greatly dependent on the operator's care.
Moreover, the mass of the introduced dental material cannot usually be ascertained exactly.
Therefore, it is known to work with a comparatively low heating-up rate in order to provide for the dental materials the possibility of bringing about a homogeneous temperature compensation, irrespective of what mass is present. Although this method is good in principle, it is diametrically opposite to the desires in the dental laboratory to save costs by means of a short production cycle.
Furthermore, U.S. Pat. No. 6,025,065 has, however, also disclosed combining an extremely high heating-up rate of more than 100° C./min with a high temperature of 1300° C. to 1600° C. Although the sintering furnace therein is in principle extremely well suited to the rapid sintering of materials, the dimensional accuracy thereof is of lesser relevance. Such a furnace is not suitable, however, for dental materials.